1. Field of the Invention
This invention relates to a woven slide fastener of the type in which fastener elements formed of a continuous monofilament in the shape of a coil are woven into a longitudinal side portion of a tape fabric at the same time that the tape fabric is woven. Hereafter, the fastener elements shall be referred to simply as "elements".
2. Description of the Prior Art
In the prior art, the coil-shaped elements of the woven slide fastener of the foregoing type are woven into the tape fabric under a condition in which the continuous monofilament, which is much thicker and sturdier than the weft and warp threads of the fabric, is bent into a coil-shaped configuration. Consequently, the fastener chain tends to stretch or elongate in the longitudinal direction and the coil loops tend to become skewed. More specifically, stability of coil spacing and the desirable upstanding attitude of the coil loops are difficult to maintain merely by weaving the elements into a longitudinal side edge of the tape fabric. Various attemps have been made to improve upon this problem. In one arrangement, such as disclosed in the specification of Japanese Patent Publication No. 46-7018, the warp threads at portions where the elements are woven are arrayed more densely than the warp threads constituting the main body of the tape fabric. While this arrangement prevents collapse of the coil loops, longitudinal expansion and contraction of the fastener chain cannot be prevented, and the problem of element spacing stability remains unsolved. Further, as disclosed in the specification of Japanese Patent Application Laid-Open No. 56-60504, a binding warp thread is so arrayed as to run astride the tops of two elements and pass below a foundation weft thread between these two elements, thereby forming double weft threads arranged between the elements into a loop and disposing the weft threads as a pad between upper and lower leg portions of the elements. This enhances element resistance against twisting and skewing to improve spacing stability. However, since the binding warp threads are clustered by the weft threads, the fastener chain is increased in thickness and loses pliability.